The Presence of Human Papillomavirus- 16/-18 E6, p53, and Bcl-2 Protein in Cervicovaginal Smears from Patients with Invasive Cervical Cancer1

Cervical cancer is the second leading cause of death from cancer in women worldwide, and recent epidemiological studies have strongly implicated the sexually transmitted human papillomavirus (HPV) as a causative agent. The ability of high-risk HPVs to contribute to malignant progression seems to depend on expression of the viral E6 and E7 oncogenes. The E6 oncoprotein forms a complex with the cellular tumor suppressor protein p53, leading to degradation of p53 via ubiquitin-dependent proteolysis. Thus, E6 expression results in the loss of p53 function in cells, including stimulation of apoptosis and inhibition of the expression of the antiapoptotic protein bcl-2. Recently, we found increased bcl-2 expression in cervical carcinoma cell lines containing mutated or E6-inactivated p53 (X. L. Liang, S. Mungal, A. Ayscue, J. D. Meissner, P. Wodnicki, G. Gordon, S. Lockett, and B. Herman. J. Cell. Biochem., 57: 509-520, 1995). Based on these findings, we examined Papanicolaou smears from 94 women with varying degrees of cervical disease for the presence or absence of p53, HPV-16/-18 E6, and bcl-2 proteins using immunofluorescence microscopy. Our findings indicate that there is a statistically significant, inverse association between the presence of p53 and invasive cervical disease Lodds ratio (OR), 0.3; 95% confidence interval (CI), 0.1-0.7]. Moreover, the odds of Received 9/27/95: accepted 219/96. The costs of publication of this article were defrayed in part by the payment of page charges. This article oust therefore he hereby marked adveriiseme,ti in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. I This work was carried out in Dr. Herman’s laboratories at the University of North Carolina at Chapel Hill and was supported by NIH Grants AGIOIO4 and AG13797 and American Cancer Society Grants FRA-383 and CB-85. 2 Suppsned by a Yansagiwa-Yoshida Memorial International Study Grant from the International Union Against Cancer. ‘ To whota requests for reprints should be addressed, at Department of Cell Biology and Anatomy. CB 7090, 232 Taylor Hall. University of North Carolina at Chapel Hill. Chapel Hill. NC 27599-7090. Phone: (919) 962-0350; Fax: 9I9) 966I 856: E-mail: bhgf6 med.unc.edu. being diagnosed with an invasive stage of cervical cancer were 3.7 times higher (95% CI, 1.6-8.8) for women positive for the E6 protein and 17 times higher (95% CI, 5.5-58.3) for women positive for the bcl-2 protein compared with women negative for E6 or bcl-2. Women with invasive cervical cancer were also 4.59 times more likely to test positive for the presence of more than one marker (95% CI, 1.8-1 1.8). f analysis demonstrated a strong association between the presence of E6 and bcl-2 (P < 0.001) as well as between the presence of E6 or bcl-2 and diagnosis (P = 0.015 and < 0.001, respectively). In the multivariate analysis, the presence of bcl-2 (OR, 18.8; 95% CI, 5.5-67.8) and age at diagnosis ( 50 years: OR, 7.8; 95% CI, 2.5-24.5) showed significant association with invasive cervical disease. These findings indicate that: (a) the presence of the bcl-2 protein is strongly associated with the development of invasive cervical disease; (b) the pattern of the presence of high-risk HPVE6, p53, and bcl-2 proteins may be useful for identifying women at increased risk for the development of invasive cervical cancer; and (c) a defect in apoptosis may partially underlie the development of cervical cancer.